Longest Substring Without Repeating Characters

Problem Statement

Given a string s, find the length of the longest substring without repeating characters. A substring is a contiguous sequence of characters within a string.

Constraints

• 0 <= s.length <= 5 * 10^4
• s consists of English letters, digits, and symbols.

Examples

Example 1

Input: s = "abcabcbb"

Output: 3

Explanation: The answer is "abc", which the length of the longest substring without repeating characters.

Example 2

Input: s = "bbbbb"

Output: 1

Explanation: The answer is "b", with the length of 1.

Example 3

Input: s = "pwwkew"

Output: 3

Explanation: The answer is "wke", which the length of the longest substring without repeating characters.

Example 4

Input: s = ""

Output: 0

Explanation: The answer is an empty string, which the length of the longest substring without repeating characters is 0.

Hints

• A common approach to solve this problem is by using the sliding window technique.
• Keep track of the characters you have seen so far in a set or a hash map.
• Expand the window to the right and shrink the window from the left as you encounter duplicate characters.
• Update the maximum length whenever you find a longer substring without repeating characters.